1. Field of the Invention
The present invention relates, in general, to a method for fabricating a metal wire of semiconductor devices and, in particularly, to the use of SF.sub.6 plasma treatment in fabricating a metal wire of semiconductor devices, thereby leaving no residue of the conductive material on an insulating layer.
2. Description of the Prior Art
With large resistance, the polysilicon layer used for semiconductor devices is a cause for the decrease in the operational speed of semiconductor devices. As a conductive passage, a metal wire is employed to reduce the resistance.
In order to better understand the background of the invention, a description will be given of a conventional process for fabricating a metal wire of semiconductor devices in conjunction with FIGS. 1 and 2.
In FIGS. 1 and 2, conventional process steps for fabricating a metal wire of a semiconductor device are shown, leaving residue.
To fabricate a metal wire, a substrate 1 is first covered with an insulating film 2 on which a barrier metal layer 3, an aluminum metal layer 5 and a reflection-preventive film 6 are, in sequence, deposited, as shown in FIG. 1. Thereafter, a photoresist pattern 7 is formed on the reflection-preventive film 6.
Usually, the barrier metal layer 3 is made from, for example, titanium or titanium nitride film, the aluminum metal layer 5 from, for example, Ai--Si--Cu, and the reflection-preventive film 6 from, for example, titanium nitride film.
With the photoresist film pattern 7 serving as a mask, the reflection-preventive film 6, the aluminum metal layer 5 and the barrier metal layer 3 are, in order, etched to form a metal wire 8, which is followed by the removal of the photoresist film pattern 7, as shown in FIG. 2. At the moment, the barrier metal layer 3 leaves residues 3' on the surface of the insulating film 2. They cause a bridge between neighboring metal wires 8, forming a short circuit.
When the aluminum metal layer of Al--Si--Cu is deposited on the surface of the barrier metal layer 3, a silicon nodule 4 grows on the barrier metal layer 3 and remains after the etching of the aluminum metal layer 5. When the underlying barrier metal layer 3 is etched off, the silicon nodule is removed together, but a part of the titanium nitride remains.